1. Field of the Invention The present invention relates to the preparation of capsules, particularly those that may contain edible ingredients, that comprise telescopically engaged capsule halves, and more specifically to a method for sealing such capsules to render them tamper-proof and tamper-evident.
2. Description of the Prior Art The capsules with which the present invention is concerned are well known and have been in broad use for many years. Such capsules are generally prepared from an edible natural substance such as gelatin, and are generally cylindrical telescopically engaging tubes, each tube having one end thereof sealed, so that upon coaxial disposition, they are capable of holding a quantity of material. Generally, such capsules are utilized in the pharmaceutical and food industries, to hold edible and pharmaceutically active materials such as medicines, vitamin preparations, and other edibles both solid and liquid. Generally, the materials from which the capsules are prepared are hydrophilic, and thereby adapted to dissolve in the intestine after ingestion.
One of the difficulties that has long been encountered in the use of such capsules as stated, has been their ability and occasional tendency to disengage from each other, whereby the contents of the capsule escape and are lost. Accordingly, the prior art is replete with numerous approaches directed to the maintenance of the sealing engagement between the capsule halves.
The problem of the disengagement of the capsule halves from each other has recently become more acute, in view of the well publicized deliberate disassembly of certain encapsulated medicaments and the inclusion therein of certain poisons such as cyanide. This deliberate act was successfully accomplished because the capsules were inadequately sealed and gave no evidence of their tampering. That is, the slip fit engagement between the capsule halves was easily disrupted and the cap part of the capsule was removed, so that the intruder was able to insert a small but lethal quantity of poison or other disruptive agent therein.
The events described above have spurred a renewed interest on the part of the industry and the public at large to develop methods and associated apparatus to render these capsules tamper-proof by the placement of appropriate indicators of tampering on the capsule. One such approach to this problem has been known for some time, and is disclosed in U.S. Pat. No. 1,861,047. In this patent, a circular band of hardened gelatin is disposed about the seam that occurs between the respective capsule halves comprising the body and the cap part that receives it. The application of the hardened gelatin band is presumed to act as a capsule seal and tamper indicator, to indicate when the capsule parts have been separated so that evidence of tampering is visually apparent.
The procedure outlined in the '047 patent and the capsules treated thereby have been found to be deficient, however, as it was possible to separate the body part from the cap part, modify the contents thereof and thereafter replace the cap and body parts in position against each other and reband the rejoined capsule so as to avoid detection of tampering.
Further deficiencies in the aforementioned technique relate to the material used to form the band. Generally, gelatin is utilized and it is found that the application thereof is difficult to control, with the result that the bands initially applied are frequently irregular, split, intermittent in extent and generally non-uniform in appearance. Also, the application of the gelatin band tends to introduce moisture into the capsule contents which in the instance of most capsule ingredients causes instability, and correspondingly drastically reduces shelf life of the contents. Likewise, if the drying system utilized in conjunctinn with the application of the gelatin band fails to function properly, excessive wetting of the capsule at the site of the band and consequent capsule deformation, particularly after large quantities of capsules are discharged into a holding drum, in accordance with conventional manufacturing practice, accentuates capsule deformation and results in increased numbers of capsule rejects.
Another bonding technique in broad use presently, is essentially a branding procedure, wherein a heated probe is applied against the outer surface of the capsule cap portion with sufficient pressure to urge it against the adjacent wall of the capsule body, and to cause both to melt superficially and thereby bond to each other.
This technique has the drawback that it frequently causes capsule deformation, by virtue of the localized heating which can contribute to increased frequency of capsule rejects. Likewise, the nature of the bond formed by this procedure is extremely local and renders the capsule vulnerable to undetectable violation, as with a scalpel or needle probe, to facilitate disengagement of the capsule halves for introduction of an adulterant.
Both of the aforementioned techniques are also inefficient and costly, as the equipment in the instance of the banding technique, is extremely expensive and limited in its rate of output. Likewise, the equipment utilized in the branding technique is complex, as one must have in addition to the branding equipment, a separate low speed machine for the purpose of holding the capsules during the branding process.
From the foregoing, it is evident that the need for an inexpensive, efficient and reliable capsule sealing technique exists. It is therefore to the fulfillment of this need that the present invention is directed.